Boat hull



Dec. 20, 1960 R. P. BANK ETAL 2,965,061

BOAT HULLv l Filed Sept. 14, 1959 2 Sheets-Sheet 1 INVENToRs vf'laraffazi Dec. 20, 1960 R. P. BANK ET AL 2,965,061

BOAT HULL Filed sept. 14, 1959 2 sheets-sheet 2 United States Patent()'i BOAT HULL Richard P. Bank, 221 Lake Shore Drive, Marlboro, Mass., andCharles P. Jacobs, Washington St., Hudson, Mass.

Filed Sept. 14, 1959, Ser. No. 839,826

7 Claims. (Cl. 114-56) This invention relates to boats and moreparticularly to small crafts such as are conventionally powered byoutboard motors, although it is to be understood that the invention isequally applicable to boats in which inboard motors are employed.

The principal objects of the invention are to provide a boat hull with abottom structure so designed as to soften the pound or bump when thecraft is driven at high speed over rough water; to insure level cruisingwithout specific passenger arrangement; to improve stability in spite ofhigh wind; to minimize water friction thereby to obtain more speed for agiven horsepower with a saving in fuel consumption and engine wear; tominimize skidding or sliding on turns and hence to increasemaneuverability; and to give maximum strength.

This is accomplished herein in accordance with the invention byproviding the hull with a bottom having a keel of convex transversesection extending longitudinally along the median line from stern tostem, the major portion of which is of uniform width, that is from thestern to a point just beyond amidships, and the remainder of which is oftapering transverse and vertical section up to the stem, and at oppositesides a plurality of ribs of convex transverse section which start atthe stern and extend forwardly to the place at which the keel commencesto taper, the remainder of the bottom of the hull being smooth.Preferably the entire bottom of the hull is convex, the ribs are aboutin the order of one-fifth the width of the keel and the forward ends ofthe ribs terminate along lines which are swept back from the keel at anacute angle.

The invention will now be described in greater detail with reference tothe accompanying drawings in which:

Fig. 1 is a perspective view of a boat of the kind designed formotivation by means of an outboard motor;

Fig. 2 is an elevation of the stern of the boat; and

Fig. 3 is a plan view of the bottom of the boat.

Referring to the drawings the boat hull comprises a shell having abottom 10, a transom 12 and sides 14 extending from the transomforwardly and converging at the stem 16. Optionally a partial deck 18, acockpit and a well 22, together with other accessories, may be provided.

The shell of the hull is preferably constructed of tiberglass molded toits final shape in accordance with customary practice, however it is tobe understood that the novel features of the bottom construction may beembodied in hulls constructed of other materials, for example plywood ormetal, with the same advantages.

According to the invention the bottom of the shell from side to side isslightly convex as indicated by the dot and dash line a-a (Fig. 2), theconvexity being so shallow that there is no appreciable roll and beingpartly offset by the ribs along the outer sides, as will be describedhereinafter.

A keel 24 which is convex in transverse section extends longitudinallyalong the median line of the hull from the 2,965,061 Patnted Dec. 2o,1960 stern to the stem, the keel extending downwardly from the line ofconvexity a-a of the bottom. Throughout the major portion of its length,that is up to and just beyond the midship, the keel is of uniform widthand depth. Forwardly of this, however, the keel 26 tapers both in widthand depth and ultimately blends with the curvature of the hull at thestem. Laterally of the keel, at opposite sides thereof, there are aplurality of ribs 28 which parallel the keel and are uniformlydistributed in parallel relation to each other, the grooves 30 betweenthe ribs 28 being substantially the same size as the ribs but obversethereto. The ribs and grooves extend forwardly from the stern parallelto the keel up to the point where the keel commences to taper, thegrooves terminating along lines b--b which are swept back from the keelat acute angles so that the ribs nearest the keel are longest and thosefurthest from the keel are shortest. As previously indicated the outermost ribs extend downwardly beyond the normal line of curvature of thebottom, acting as steps which stabilize the boat transversely.

The effect of the grooves between the ribs is to break up the surfacecontact between the water and the bottom of the hull to such an extentthat cushions of air are induced at the bow by the forward movement ofthe boat, which pass rearwardly through the grooves, yieldinglysupporting the boat on the surface of the water thereby reducing thepound, reducing skin friction and hence increasing the speed. The ribsat the same time prevent sidewise skidding due to winds or sharp turns.The combination cuts down vibration, and by holding the boat out of thewater takes advantage of the maximum power available with a minimumamount of fuel consumption.

By way of illustration only and without limitation a boat of theforegoing kind may have an overall length of 15 feet l1 inches, width of601/2 inches and depth of 341/2 inches. When constructed to theforegoing dimensions the keel is of uniform width for a length ofapproximately 9 feet 2 inches and tapers from there on to the stem. Theribs vary from the longest, which is S feet l1 inches, next to the keel,to the shortest at the outside which is 8 feet 2 inches. The bottomwhich is convex has a radius of curvature of approximately ten feet andthe keel and ribs project therebelow, the keel having a radius ofcurvature of approximately 131A inches and the ribs a radius ofcurvature of approximately 21/2 inches. The grooves between ribs aresubstantially of the same radius of curvature as the ribs. Thus the keelis approximately five times the width of the ribs.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

We claim:

1. A hull for a boat comprising a shell a portion of which constitutes alongitudinally-smooth bottom, a keel extending along the longitudinalmedial line of the bottom from stem to stern, said keel having a convexsurface of uniform width from stern to amidship and which tapers fromamidship to stem, and a plurality of laterally disposed spaced parallelconvex ribs at opposite sides of the keel which extend from the stern toamidship, said ribs being substantially narrower than the uniform widthportion of said keel, that portion of the bottom forwardly of amidshipbeing smooth.

2. A hull according to claim 1 in which the laterally disposed ribs arein the order of one-fifth of the width of the keel.

3. A hull for a boat comprising a shell a portion of which constitutes alongitudinally-smooth bottom which in transverse section is convex, aconvex keel extending along the longitudinal medial line of the bottomfrom stern to stem, said keel having a portion of uniform widthextendngfrom therstern to amidships and a tapering farthest from thekeel'are shortest, said ribs being vsubstantially narrower than theuniform width portion of said keel, that portion of the bottom forwardlyof `the ends of the ribs being smooth.

4. A hull for a boat comprising a shell a portion of which constitutes alongitudinally-smooth bottom which is transversely convex from sternV tostem, the`bottom fromrstern to amidships being of substantially uniformwidth and beyond tapering to the stem, a keel rib of convextransversesection protruding downwardly from the normal curvature of the convexbottom and extending from stern to stem along the medial line of thebottom, a portion of the keel from stern to Vamiclships being of uniformwidth and forwardly thereof tapering in width and depth and blendingwith the stem at its forward extremity, and a plurality of ribs ofconvex cross-section disposed at opposite sides of lthe keel in parallelrelation thereto, said ribs being substantially narrower than theuniform width portion of said. keel, said ribs being coextensive withthat portion of the bottom which is of uniform width and the taperingportion of the bottom forwardly thereof being smooth.

5. A hull for a boat according to claim 4, wherein the ribs also extenddownwardly from the normal curvature of the convex bottom.

6. Afhull fora boat according to claim `4, wherein the grooves betweenthe ribs are of substantiallygthe same size as the ribs but obversethereto.,

7. A hull foraboat according to claim 4,'wherein the bottoms ot thegrooveslie vsubstantially on the normal curvature of the convex bottom.

References Cited in the le of this patent UNITED STATES PATENTS1,050,517 Chaser V Jan. 14, 1913 FOREIGN PATENTS 1,063,744- France MayS,1954

